1. Field of the Invention
The present invention relates to an electrodeposition paint and an electrodeposition coated material which are used for optical apparatuses, electric appliances, acoustic machines, communication machines, home appliances, office machines, and the like. The invention has also been found to be suitable for wall materials of a clean room, for enhancing static-electricity resistance and for forming a decorative surface. The present invention also relates to a method of producing the electrodeposition coated material.
2. Description of the Related Art
Conventionally, the following methods are available for forming a coated material having static-electricity resistance and which is used, for example, in optical apparatuses, electric appliances, acoustic machines, communication machines, home appliances, office machines, and for wall materials of a clean room. The main method employed is by spray-coating a suitable substrate with a conductive paint so as to form a coating. Other methods such as filling a conductive filler in a resin, mixing a surface active agent with a resin, and the like, are also available.
However, the above conventional methods have presented problems. In the above method of spray-coating a suitable substrate with a conductive paint so as to form a coating, the volume resistivity of the coated material is varied depending on the aspect ratio of the conductive filler. For example, since a spherical conductive filler has a low aspect ratio, the targeted volume resistivity cannot be achieved unless the filler content in the paint is 50% by weight or more. Moreover, the excessive conductive filler content deteriorates the durability of the coating. Hence, it is difficult to apply such a coated material to the product, and the cost is expensive.
In order to solve the above problems, a conductive filler which has the shape of a short fiber, a needle, a scale, or a sphere having a sharp projection, and which has a high aspect ratio, is added to the paint. Only a small amount of such a conductive filler is necessary to sufficiently produce positive influences exceeding those of a spherical filler. However, the above method also possesses drawbacks, and, consequently, the resulting coated material obtained by this method is not suitable for practical use. For instance, an elongated conductive filler is hardly ever dispersed in a resin or paint, or the conductive filler may be broken, thus lowering the high aspect ratio, and further preventing quantity production.
Further, a coated material can be formed by mixing a surface active agent instead of the conductive filler, in order to solve the above problems. However, the surface active agent tends to be denatured with the lapse of time due to exposure to temperature or light, or it produces no effect in a dry atmosphere, thus deteriorating the value of the commercial product. Additionally, nonuniformity of the filling is caused and anisotropy occurs in conductive characteristics during plastic injection molding.